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By Selwyn Pearton

Pumpable emulsion explosives have been available to surface and underground massive mining operations for decades and through their unique properties offer significant advantages through improved safety, reliability and performance. Despite their advantageous properties, the benefits of pumpable emulsions have been unavailable to narrow reef mining operations due to the void in technology necessary for their successful implementation within the challenging environment. Despite efforts to promote and enhance the safety and performance of bulk emulsions for narrow reef stoping, little research has been undertaken to advance the pump technologies required for their implementation. This has resulted in a gap in knowledge and technology and as a consequence the successful implementation of a pumpable emulsion system has consistently eluded the narrow reef environment.

Jan 1, 2015

By G. Couture

"The Glencore Raglan mine Concentrator, located in Quebec’s Nunavik region, has been in operation since 1997. The nickel metallurgical plant was originally designed to process 100 tonnes per hour of ore to produce 130 000 tonnes of nickel concentrate per year at 16% Ni. The increased grinding capacity and the discovery of rich ore bodies have increased the annual production to more than 190 000 tonnes of concentrate at 19% Ni. In 2014, the Metallurgical group, with support from BBA, implemented an expert control system on the flotation circuit. This project was initiated to cope with the high variability of the concentrator’s feed. Increasing the plant recovery and final concentrate grade were also important project objectives. The implementation of the expert system ensures better control of concentrate inventory while maintaining maximum plant throughput. This paper describes the successful implementation of the new control system, the control technology selection and the flotation circuit optimization. It will also discuss the performances obtained with this new approach and the improved process stability.IntroductionThe Raglan Mine is located in Northern Quebec along the 62th parallel. It has been in operation since 1997 and was originally designed to produce 130 000 tonnes of concentrate annually at 16% Ni. The increasing of the grinding capacity and the discovery of rich ore bodies have increased the annual production to more than 190 000 tonnes of concentrate between 18 and 20% Ni."

Jan 1, 2015

By D. S. Yang, Y. D. Wang, G. Watanabe, A. P. Notaro

"Deep soil mixing (DSM) walls reinforced with steel soldier piles were installed for excavation support and groundwater control for the construction of a grade separation structure at the intersection of Warren Avenue and the Union Pacific Railroad in Fremont, California to mitigate traffic conditions during the busy commute hours and for the extension of San Francisco Bay Area Rapid Transit (BART) system. Instead of treating the DSM wall as a temporary structure, the reinforced DSM walls were integrated in the design of the permanent structures including retaining walls, and the abutments and pier of the railroad and BART bridges. The integration of steel members inside the DSM wall as part of the permanent structures is an innovation which facilitates the use of top down construction techniques to speed construction and utilizes the steel soldier piles that would have been disregarded after the use as a temporary shoring wall. This paper will review the background of the project and DSM method and present the design and construction of the DSM wall composite structure for this grade separation project.INTRODUCTIONUsing the concept of mixed-in-place piles initiated in the 1950’s in the United States, Japanese contractors in the late 1960’s and early 1970’s installed single mixed-in-place soil-cement piles along a row to create a wall for excavation support and groundwater control. Due to the high groundwater conditions in most of the coastal cities in Japan, wall continuity and uniformity became the requirements of soil-cement walls for reliable groundwater control to minimize ground movement and impacts to adjacent buildings and facilities. In late 1970s, Seiko Kogyo, Co. Ltd. developed the Soil Mix Wall (SMW) method, which uses a triple auger mixing tool to improve the uniformity and continuity of soilcement wall. The SMW method is considered a wall installation method in contrast to the Cement Deep Mixing (CDM) method, also developed in Japan, for ground stabilization in soft soils, especially in the marine environment. In the U.S., generic terms like DMM (Deep Mixing Method), DSM (Deep Soil Mixing) or CDSM (Cement Deep Soil Mixing) are used by various government agencies and private organizations to describe the soil mixing technologies without differentiating the origin, procedure and application. The method used in this project is called DSM method by the project owner, Santa Clara Valley Transportation Authority (VTA), to produce a single continuous soil-cement wall for use as shoring wall and composite structure. The mixing tool for DSM wall installation can vary from 3 to 6 mixing augers. Due to the need to install steel soldier piles into the DSM wall for resisting lateral forces, high water cement ratio slurry with bentonite is used to produce low strength soil-cement, generally in the range of 70 to 100 psi (500 to 690 kPa), with high fluidity to facilitate the installation of steel soldier piles. To maintain the wall continuity for groundwater control, overlapping of one full DSM column is made between neighboring elements using two types of installation procedures as illustrated in Figures 1a and 1b. Steel soldier piles, as shown in Figure 2, are used to reinforce the soil-cement wall to resist the lateral shear force and bending moment induced during the excavation."

Jan 1, 2015

By R. V. Ramani, K. V. Raj

"The air flow problems in open pit mines are complex. Computational fluid dynamics (CFD) models provide a detailed knowledge of the airflow pattern and velocity distribution, temperature, and pollutant concentration within an enclosed domain of the open pit. A range of turbulent model can be selected for varying complexity and accuracy. Pollutant transport models, however, differ in their assumptions and structure as well as in the algorithm they use; as a result, prediction varies from model to model. This paper presents a study of pollutant transport in an actual open pit mine under stable boundary layer. The objective is mainly to test two turbulence models using the same input conditions, model constants, and similar geometry. Measured data are used to compare results of the two CFD models, namely, the kappa-epsilon (?-e) model and the Large Eddy Simulation (LES) model. Despite the complex synoptic situations, different meteorological input data and the fast changing conditions, the simulation results from both the models are in good agreement regarding the dispersion of pollutants.INTRODUCTION Modeling of contaminant transport under Arctic air inversion is an important step for an assessment of the amount of pollutants within the open pit. The Airflow in open pit mines is of larger scale and does not follow the principles of pipe flow. The air flow problems in actual open pit mines are thus far more complex. CFD models provide a detailed knowledge of the airflow pattern and air velocity distribution, temperature, and pollutant concentration within an enclosed domain of an open pit. There is no known application of CFD in three-dimensional modeling of air flow in large open pit mines. Two equation RANS kappa-epsilon (?-e) and Large Eddy Simulation (CFD) models, however, have been developed to solve the stable boundary layer (SBL) problems in Atmospheric Sciences (Baklanov 2000, Basu and Porté-Agel 2006, Dop and Axelsen 2007, Bandopadhyay et al. 2014). Because an exact flow situation in open pit mines is not known a-priori, it is therefore, necessary to investigate various turbulent models to identify the appropriate model that would simulate the flow phenomena with reasonable accuracy, and predict the contaminant distributions within the pit. Dispersion models differ in their assumptions and structures as well as in the algorithm they use and, as a result, predictions vary from model to model. Furthermore, it is also important to investigate the behavior of a CFD model in simulating a complex phenomenon such as the transport and distribution of contaminants in open pit mine under Arctic air inversion. The simulation of an enhanced period of turbulence in SBL is of particular interest because traditional air pollution dispersion models cannot explicitly treat such intermittent events, and yet the SBL is often the worst-case scenario in an open pit pollution transport"

Jan 1, 2015

By Farshad Rashidi Nejad, Ali Asgari, Sanaz Norouzi

Blasting is known as the first step of rock breakage in mines. An indication of the importance of blasting is that more than 1 billion kg (2.2 billion lb) of explosives are used annually in Australia and 3 billion kg (6.6 billion lb) in the United States for rock breakage, more than 85% of which is used in the mining industry. The notion that blasting, as the first step of comminution, plays a significant role in crushing and grinding energy consumption is not an unfounded thinking. It can be noted that the comminution electrical energy consumption decreases in these ways: First, if the feed size to the primary crusher is decreased, less energy will be required to crush the ore to the same product size. Second, a decrease in work index (Wi) related to additional macro fracturing and micro fracturing within individual fragments.

Jan 1, 2015

By K. Thuro, S. Schneider, H. Kasling, P. Ellecosta

"One of the most important methods for material testing is the characterization of the hardness, which is defined as the resistance of a material to the penetration of another one. The methods according to Brinell, Vickers, Rockwell and Knoop are today the most common and standardized tests for metal. As they are developed for predominantly ductile materials like steel, they can’t easily be applied to rocks which react much more brittle under indentation. But just as steel, rock is composed of different minerals and has a specific microstructure. Its mechanical parameters are connected with the particular grains, their cohesion and interlocking, just like steel.The abrasivity of rocks and the accompanied wear of drilling tools today are mainly determined by simple and fast laboratory tests such as the Cerchar abrasivity test or the rubber wheel test. Such laboratory tests are good tribological tests, but there are limits. The Cerchar abrasivity test for example has weaknesses in extreme cases, that mean soft or very hard rock types. This leads to an underestimation of abrasivity, e.g. in poorly lithified sandstones or very hard, fine grained and extremely abrasive rocks. As mentioned, hardness characterizes, depending on the type of deformation, predominantly plastic (metal) or elastic properties (rubber). Rocks are in the range between these two extremes. Since the rock drilling process can be seen as a kind of penetration process on macroscopic and microscopic scales, we picked up the idea to characterize the interaction of rock materials and TBM-disc-cutters with hardness tests. In addition, this supports for a better understanding of the wear process on disc cutters. We used the hardnessdisparity concept after Cardu & Giraudi (2012) because wear can be understood as the interaction between the wear part and the material which causes the wear (tribological system). Several rock-forming minerals and some fine to coarse-grained monomineralic and polymineralic rocks were tested. In contrast to Cardu & Giraudi, we used in the first step of investigations the method after Vickers with loads up to 294.2 N (HV 30), depending on the estimated hardness to get bigger indentations and therefore as well information about the cohesion and interlocking of the minerals/grains. We also tested several associated disc cutters. First results show that with higher loads (HV 5 - 30) and at least 15 indentations, we get a structural hardness in fine-grained rock samples, which allows a good characterization of the elasticity and brittleness. Nevertheless, for the coarse-grained rock samples we need up to 40 indentations for a good characterization. Using this method, a prediction of disc cutter wear is feasible taking into account the hardness of the disc cutter steel. In this paper, we would like to present this approved method in material sciences to derive an additional parameter for the characterization of rock abrasivity and wear."

Jan 1, 2015

By D. Men, R. Q. Honaker, J. C. Hower

"Maceral separation is one possible technique to expand coking coal resources, either by increasing the blending ratio of non- or slightly caking coal or rationally utilizing the coking coal according to the different behaviors of macerals in coking. The success of maceral enrichment for a given coal using flotation is dependent on the differences in flotation kinetic rate among macerals. This paper presents the flotation rates and zeta potentials of the vitrinite-rich and inertiniterich maceral concentrates obtained from six coal samples of different ranks – from high-volatile B bituminous coal with mean random vitrinite reflectance (Rrandom) of 0.64 percent to low-volatile bituminous coal with Rrandom of 1.73 percent – using a float-sink procedure. The flotation results show that vitrinite-rich concentrates can be produced in tap water using froth flotation only with frother for the high-volatile B and A bituminous coal samples, but there was no good performance for the high-volatile C bituminous and medium- to low-volatile bituminous coal samples. The zeta potential results show that froth flotation could probably separate the high-volatile C bituminous coal samples well by adjusting pH, but there was no good performance for the higher-rank coal samples. IntroductionMetallurgical coke is used in blast furnaces for steel production and is produced by the carbonization of coking coal. Because caking coals are rare and expensive, they are often blended with non- or slightly caking coals. Considering the tight supply-demand situation for coking coal in China, it is important and urgent to develop highly efficient technologies for rationally utilizing and expanding coking coal resources (Mochizuki et al., 2013)."

Jan 1, 2015

By Chad W. Brown

"A study of five commercially available solvent-extraction diluents in combination with three commercially available extractants under sub-Saharan African copper solvent-extraction conditions yielded intriguing results. A variety of physical and chemical property analyses showed that the diluents have some property differences, but overall the properties are similar and provide comparable solvent-extraction performance. Although each physical chemical property technique provides useful information, no individual test result suffices for prediction of diluent performance. Furthermore, a diluent should be evaluated within the conditions for which it is targeted to determine a true measure of performance. Overall, the diluents studied possess appropriate physicochemical properties for sub-Sahara Africa copper solvent-extraction conditions and can be utilized to achieve efficient, safe and reliable operations. INTRODUCTION Background Today, commercial SX diluents are available globally from a limited number of manufacturers. Production quality and consistency of these diluents have improved tremendously over the past 20 years. For example, diluent flash points have been increased incrementally to improve transport and handling while reducing fire hazards. In addition, properties have been successfully modified to minimize evaporative losses, ultimately reducing SX plant raw material costs. Diluent manufacturers have also focused on meeting performance requirements of SX plants, including eliminating components detrimental to SX operations, such as olefinic groups that can react with various species resulting in changing phase-disengagement properties over time, as well as ensuring that proper hydrocarbon components are present within diluent mixtures to maintain good reagent–metal complex solubility. These challenges have been met in the midst of ever-increasing stringent environmental regulations. Sub-Saharan Africa copper SX operations pose a unique set of conditions for diluents due to inherent ore compositions and the associated high reagent concentrations required for complete copper extraction. Chevron Phillips Chemical Company, LP has been manufacturing hydrocarbons and hydrocarbon-based diluents since the mid-80s, applying this experience to identify the physical properties considered crucial for proper performance in SX operations. This paper documents the findings of a study utilizing commercially available diluents in combination with extraction reagents commonly utilized in African SX operations to evaluate the relative performance of the diluents under sub-Saharan Africa copper SX conditions."

Jan 1, 2015

By Zheng Shuangying

The vibration effect of the buried oil pipeline caused by tunneling blasting affects the pipeline safe transportation, tunnel construction schedule and its construction cost. The dynamic response characteristic of the buried pipeline under blast loads is the foundation of designing blasting scheme as well as the prerequisite to pipeline safety. Taking the blasting engineering of Xiannvyan tunnel passing through a buried oil pipeline of the high-speed railway from Xi’an to Chengdu as the background, according to the space relation between tunnel and pipeline as well as the charge structure of V-cut blasthole, the 3D non-linear dynamic finite element model of tunnel-pipeline was established in the light of the equivalent explosive. The vibration response of the ground surface over pipeline resulting from V-cut blasting was simulated by LS-DYNA finite element program. Comparing with the measured vibration velocity waveforms in site, the accuracy and reliability of the numerical model are well verified. On the base of the simulation method, the coupling dynamic response characteristic between buried oil pipelines and soil was further studied and the Von-Mises stress distribution of pipeline wall was obtained. The safety of buried oil pipeline was quantitatively analyzed through the inside stress data of pipeline given by the simulation calculation above. The analytic results show that the maximum vertical vibration velocity of pipeline on the interface between pipeline and soil is 1.62~5.07 times as large as that of soil. When the buried pipeline is located over the tunnel and 13 m (42.6 ft) away from tunnel, the maximum vertical vibration velocity of ground surface caused by V-cut blasting with charge weight 17 kg (28.6 lb) is 3.17cm/s (1.25 in/s) and the vertical peak vibration velocity of pipeline top is about four times as the ground location directly above the pipeline. Meanwhile, the peak dynamic stress of the buried pipeline caused by blasting vibration is only 2.35% of the allowable stress of steel pipeline. The maximum superimposed stress of the blasting dynamic stress and the hoop stress produced by the pipeline internal pressure is 242.56 MPa (35 180.36), which implies that the buried oil pipeline is completely safe under the conditions of the given tunnel blasting scheme.

Jan 1, 2015

By Ruilin Yang

The vector sum peak particle velocity (PPV) of blast vibrations describes the blast vibration intensity more completely than the PPV of a single component waveform. It is more logical to use a vector sum PPV as a vibration limit than using a single component PPV. In 1980 the USBM recommended the frequency related peak particle velocity criterion. So far this method has been only applied to single component waveforms, but not to the vector sum PPV since there is no method available to associate a frequency to the vector sum PPV. The present paper describes a method to define a principal frequency associated with vector sum PPV. The method is based on the weighted average of the principal (zero-crossing) frequencies of the three tri-axial components at the time of the PPV.

Jan 1, 2015

By G. Song

"SynopsisAccording to the overlying rock strength and thickness of 10 shallow coal seams in China, the strata are classified into four types: weak and laminated strata (hereinafter referred to as WL), weak and massive strata (WM), strong and laminated strata (SL), and strong and massive strata (SM). The four types of strata, together with longwall panel height (M), panel length (L), and seam depth (H) are factors that influence the loads on hydraulic power supports. Principal component analysis was used to study the seven influencing factors. It turns out that seam depth (H) is multicollinear with WL, WM, SL, and SM. Thus the enumerated seven factors are divided into two models. In Model 1, six factors; panel height, panel length, and layer thickness of the four type strata are involved. In Model 2, three factors; panel height, panel length, and seam depth are included. Using multivariate regression analysis, two equations to calculate loads on supports are obtained for each model. The equations were applied to shallow coal seams. The equation of Model 1 is more accurate than that of Model 2, but Model 2 could be further used in deep coal seams. The equations were coded through VB programming to simplify the calculation.IntroductionTo ensure coal production in the long term, the focus of coal mining has been gradually shifted to the western areas of China in recent years due to rich coal resources in this region. Most of the coal seams in this area are shallow but the support loads are abnormally high. In these circumstances, the chock loads estimating methods used in the past do not work. If the rated working resistance of a support is larger than needed, the shield is unable to fully perform, while a lower working resistance would lead to accidents like shield crushing or even casualties. This problem is frequently found in shallow coal seams such as Shenfu-Dongsheng, Yulin, Tuha, Lingwu etc. (Zhang, 2011). Thus, to ensure safety and efficiency during mining, the estimation of support loads and selection of supports are of great significance."

Jan 1, 2015

By P. V. Chandramohan

"In ports, piled berths are designed and constructed for berthing of ships with a finite draught. Piles in a bridge foundation also have a large free stand above scoured level. The piles of these structures have to withstand large horizontal forces imparted by the impact of the approaching vessels or due to longitudinal and transverse action in a bridge. It is also imperative that these piles have to project out of the dredged / scoured bed. These piles are normally designed as slender compression members subjected to bending also. They are subjected to vertical load tests for assessing the soil resistance. Lateral load tests, as a rule, are also stipulated. IS and IRC codes stipulate a deflection criteria for lateral load test to arrive at the capacity. These tests are usually conducted on a working pile by jacking out two piles. At the time of the test, pile will be free headed. But in service, piles are fixed head. There is a large difference in deflections between a fixed head and a free headed pile. Besides, a free headed pile will be subjected to a much higher bending moment than the fixed head one. This will put the working test pile under risk of breaking during the test. The problem is analyzed with case studies. INTRODUCTION Vertical capacity of piles is assessed by static formulae. This formula is based on the soil properties obtained from random soil exploration and laboratory and in-situ testing. Since soil is not a homogeneous medium, properties can vary. The design parameters taken for computations may be different from the ones at the interface of the pile with the soil. The best way is to find out is by a load test. The code IRC:78-2014 has rightly stated that initial load test is part of the design process. This is true with the vertical load test. But there are certain problems with the purpose and inference of the lateral load test. In both the tests the criteria for acceptance is the quantum of movement of the point of application of the load. In the former, the movement is vertical and depends more on the compression of the soil than the compressive strain in concrete. But in the latter, this movement is partly on account of the flexural rigidity of the pile and partly due to the horizontal compressibility of the soil. The role of rigidity of the pile is more when compressibility of the soil is higher. Lateral load test is done by jacking one pile against another because it is difficult to get an independent horizontal reaction. Please see Fig.1 Photo."

Jan 1, 2015

By D. Newman

"This paper discusses the author’s work on international law norms of consultation with Indigenous communities and examines unexpected corporate stakeholder impacts on these norms. Customary international law, which governs the area, does not traditionally refer to corporate conduct. This paper surveys several sources on developing international law on consultation obligations; it also discusses the impacts these norms can have on corporate stakeholders in the mining industry. Finally, it asks how interactions of corporate stakeholders in this area can indirectly impact future law and suggests implications for different business models in the mining sector.RÉSUMÉ Le présent article traite du travail de l’auteur sur les normes de consultation avec les communautés autochtones contenues dans le droit international et examine les impacts inattendus des parties prenantes sur ces normes. Le droit coutumier international, qui gouverne ce domaine, ne réfère traditionnellement pas à la conduite des sociétés. L’article analyse plusieurs sources traitant du développement de nouvelles lois internationales sur l’obligation de consulter; il traite aussi des impacts que ces normes peuvent avoir sur les parties prenantes dans l’industrie minière. Finalement, il pose la question à savoir comment les interactions des parties prenantes dans ce domaine peuvent avoir un impact indirect sur les lois futures et il suggère des implications pour divers modèles d’affaires dans le secteur minier."

Jan 1, 2015

By J. S. Lee, R. K. Massarsch

"A 3.2 km long immersed road tunnel forms part of the Busan-Geoje Fixed Link in South Korea, which connects Korea's second largest city Busan, with the island of Geoje. To ensure the water tightness of the joints of the segmental tunnel structure and to limit the forces in the shear keys, the differential settlements have to be limited. This was achieved by extensive soil improvement of the marine clay below the tunnel with cement deep mixing (CDM) and sand compaction piles (SCP). This paper focuses on the characteristics of the marine clay, the basic design principles, layout and constructional issues of the CDM soil improvement, and numerical and numerical analyses to predict settlement and stability.INTRODUCTIONThe Busan-Geoje Fixed Link consists of two short cut & cover tunnel access ramps, a 3.2 km long immersed tunnel (Figure 1) and two long span cable stayed bridges. The tunnel consists of eighteen concrete elements each of 180 m length having a rectangular cross section of 26.5 m in width and 10 m in height. The tunnel elements are cast in a dry dock on shore and floated out to the sea, immersed in their final positions on a gravel bed in pre-excavated trench and connected to each other by a dual gasket system. The water depth was up to 50 m making the tunnel of the deepest yet constructed. After immersion, the tunnel is protected by backfill material at the sides and rock armour on top. Each tunnel element consists of eight 22.5 m long segments. The joints between the segments and between the tunnel elements are equipped with EDPM water stops, Omega seals and concrete shear keys. The longitudinal displacement behaviour of the segmental tunnel structure in the varying ground conditions represents a complex soil-structure interaction problem which has been modelled with a FEM structural model representing the tunnel, the joints and with springs to represent the soil that are derived from the PLAXIS soil/foundation models. In order to ensure the water tightness of the joints which have limited opening capacity and to limit the forces in the shear keys, differential longitudinal settlements have to be limited. This is achieved by limiting the variations in subgrade modulus along the alignment and it in practice means that differential settlements are limited to a few tens of millimetres. Without soil improvement of the marine clay below the tunnel, long-term tunnel settlements of up to 400 mm were predicted when taking into account the likely variations in the trench profile, backfilling and uncertainties in the soil properties. Such large total settlements led to large variations in the sub-grade reaction along the alignment, which in turn resulted in significant differential settlements, unacceptable joint opening and large shear key loading. It was therefore decided to carry out extensive soil improvement with cement deep mixing (CDM) (CDIT, 1999) and sand compaction piles (SCP) (Kitazume, 2005) after studying a number of foundation alternatives."

Jan 1, 2015

By Y. Luo

"It is generally known that spontaneous combustion potential is a function of coal rank, with low-rank coals having high susceptibility to self-ignition and high-rank coals having low potential. To establish this functional relationship and use it as an engineering tool to identify the propensity of coal to self-heat, both rank and spontaneous combustion potential should be quantified. ASTM D388 is normally used to classify coals by rank, but this classification system can only serve a qualitative analysis. To classify coals by their potential for spontaneous combustion, the self-heating temperature (SHT) method originally developed by the U.S. Bureau of Mines (USBM) was used by Litton and Page (1994) to correlate coal rank with spontaneous combustion potential. In that method, the SHTs of coal determined by an adiabatic experiment are linked with proximate analysis results through a proposed concept known as the “moist fuel ratio.” This ratio is a function of moisture, volatile matter and fixed carbon, all of which have widely different content percentages in different ranks of coal and have strong relationships with coal rank. However, the method is highly empirical, and there is large standard deviation between experimental data and calculated results. The equation correlating the coal quality parameters to determine SHT should be improved with more experimental data.This paper reports on the development of a new system for predicting the spontaneous combustion potential of U.S. coals, based on coal composition data from the U.S. Geological Survey’s coal quality database. First, the user is provided with a quantified classification of coal rank. Second, based on experimental SHT data covering a wide range of ranks from lignite to low-volatile bituminous coal, the original USBM correlation for predicting SHT is improved for the respective rank of coal. The relationship between the rank and SHT of U.S. coals was developed and plotted. The plot diagram can be used for a quick estimate of the SHT of a U.S. coal and as a cost-effective tool for the initial risk assessment of a new mine development."

Jan 1, 2015

By M. Mohammadijoo, J. B. Wiskel, D. G. Ivey, S. Kenny, H. Henein

Cold-wire tandem submerged arc welding (CWTSAW) has recently been developed as a novel welding technique to replace the conventional tandem submerged arc welding (TSAW) process and improve the productivity of pipeline manufacturing. The process involves two electrodes with arcs and one electrically cold electrode. Since heat-input of the welding process is a key factor affecting the properties of the weld metal (WM) and the heat-affected zone (HAZ), and the additional cold-wire affects the heat introduced to the weldment, it is of interest to investigate property and geometry changes in the WM and HAZ when a cold-wire is added to the welding process. In the current research, the CWTSAW process is investigated and optimized by correlating the main welding parameters with the micro-hardness of the WM and HAZ and the geometry of the weld, i.e., the bead width (BW), penetration depth (PD), reinforcement area (RA) and coarse grained heat-affected zone (CGHAZ) area. Three statistical and mathematical methods are employed to optimize the CWTSAW process in terms of the mechanical properties and WM and HAZ geometry of a typical microalloyed steel used for pipeline manufacturing.

Jan 1, 2015

By Tom Snyder, John Brulia

Part 4 is the final article by the authors on hazardous materials (HM)transportation safety and compliance for U.S. shippers and carriers who offer and transport commercial explosives in commerce on public highways. This article covers hazardous materials (HM) cargo segregation and securement of non-bulk packaged explosives.

Jan 1, 2015

By D. E. Deegan, P. M. Keeley, N. A. Rowson, T. Stachowski

An investigation into the use of Tetronics International’s thermal plasma technology based pyrometallurgical smelting process for the recovery of both platinum and rhenium was conducted. 1000 kg of Pt-Re catalysts containing 0.36 wt% Pt and 0.21 wt% Re was blended with fluxing agents, reducing agents and an iron based collector metal precursor and then fed into a plasma furnace over five individual trials at Tetronics International’s facility in Swindon, UK. Both platinum and rhenium partitioned to an iron rich collector metal phase in the furnace, which formed in-situ and accumulated beneath a less dense slag phase, derived from the inorganic substrate of the catalyst, and was easily separable. The levels of Pt and Re concentration achieved in the iron collector made it suitable for subsequent final refining. Technical recovery efficiencies of =98% for both platinum and rhenium were achieved and the concentrations of the metals in the recovered metal bullion were 2.23 wt% Pt and 1.35 wt% Re.

Jan 1, 2015

By Tim Miller, Michael M. Murphy, John L. Ellenberger, Gabriel S. Esterhuizen

"A limestone mine in Ohio has had instability problems that have led to massive roof falls extending to the surface. This study focuses on the role that weak, moisture-sensitive floor has in the instability issues. Previous NIOSH research related to this subject did not include analysis for weak floor or weak bands and recommended that when such issues arise they should be investigated further using a more advanced analysis. Therefore, to further investigate the observed instability occurring on a large scale at the Ohio mine, FLAC3D numerical models were employed to demonstrate the effect that a weak floor has on roof and pillar stability. This case study will provide important information to limestone mine operators regarding the impact of weak floor causing the potential for roof collapse, pillar failure, and subsequent subsidence of the ground surface.IntroductionMassive roof falls extending to the surface at a limestone mine in Ohio have been studied collaboratively by the National Institute for Occupational Safety and Health (NIOSH) and the mine owners. This paper provides a summary of the sequence of events leading to observed instability and presents a numerical modeling analysis that investigates the role a weak floor can have on roof and pillar stability.This study builds upon previous NIOSH research in underground limestone mines undertaken by way of a survey that analyzed performance of pillars in 34 different stone mines in the Eastern and Midwestern United States between 2005 and 2009 (Esterhuizen et al., 2011). This survey led to the development of underground stone mine pillar design guidelines based upon a “stability factor” for the pillar system. The factor is compared to operational experience to determine ranges of values that are typical of stable pillar systems. A software package titled Stone Mine Pillar Design (S-Pillar) was developed for easy application of these guidelines (Esterhuizen and Murphy, 2011).Weak floor in the present case study departs significantly from cases included in the previous NIOSH research, in that none of the 34 study mines had weak floor issues. Moreover, this case study is the first in which a weak floor has been monitored routinely as roof falls are occurring. A detailed report on the observations and measurements taken at the mine has been published (Murphy et al., 2015). The previous observations led to the conclusion that although there were weak bands in the pillar, the weak floor was the significant defect that led to the instability issues. The pillars were initially mined in 2004, approximately 10 years before the instability issues began to occur. The objective of this study is to use numerical models to analyze a variety of floor strengths and the impact of moisture content to find the critical point at which the floor becomes unstable, leading to long-term instability issues."

Jan 1, 2015

By Guo Qian, Du Guangyin, Deng Yongfeng, Liu Songyu, Wang Ningping

"Metakaolin (MK) can efficiently enhance the strength and the impermeability of concretes and mortars. However, it has rarely been attempted in admixtures of cement-stabilized soils until presently. As deep mixing method is wildly used in ground improvement, the strength of cemented soils (soilcrete) and the applicability of the MK should be considered. This paper focuses on the macro-strength development of cement-stabilised silty soil mixed with MK. The result shows that the addition of MK can enhance the unconfined compressive strength of the soilcrete, which attributes to a combination of the rates of OPC hydration and the MK-CH reaction. Note that the strength of soilcrete was influenced by the properties of soil, water-to-binder mass ratio (W/B) in admixtures, which needs to be reconsidered since the binder mass composes that of cement and MK totally.INTRODUCTIONCement was used in ground modification techniques, such as the jet grouting, deep mixing method (DMM) which was put into practices in Japan and Nordic countries in the middle of the 1970s, and then spread to China, South East Asia[1]. For last decades, fly ash, slag or silica fume was mixed with cement to form the new cement base stabilizing agent in the view of economy and performance improvement. The mechanical behavior of these soil-binder admixtures (nominated as “soilcrete”), was investigated. But the soilcrete modified with the metakaolin (MK) was still not investigated much and lots of further work needs to be conducted.Some laboratory experiments of the soilcretes modified with MK have been taken[2~4]. Kolovos et al. (2013) indicates that the unconfined compressive strength has a more significant improvement when W/B equals 0.4 than that when W/B equals 1.20 concerning the water-to-binder mass ratio (W/B). Sonebi et al. (2013) investigates the mechanical behaviors of cement grouting containing MK with W/B equals 0.4, and also found the effectiveness of the addition of MK. Zhang et al. (2014) performed the studies on Lianyungang marine clay improvement showed that MK obviously enhanced the quality of cemented soils.In this paper, the strength of soilcrete modified with MK is further investigated, where the unconfined compressive strength at different curing time, the content of MK and cement (w/w) in lab conditions was discussed."

Jan 1, 2015